Screen plug for core barrels



Dec. 16, 1930. R. c. BAKER 1,784,886

SCREEN PLUG FOR CORE BARRELS F'iled DeC. 24, 1927 Zyl Patented Dec.v 16, -1930 ,UNTTED STATES PATENT OFFICE BEUBEN C. BAKER, OF COA'LINGA, CALIFORNIA, ASSIGNOR TO BAKER OIL TOOLS, INC.,

l A CORPORATION 0F CALIFORNIAV SCREEN PLUG Fon conn BARRELS Application mearecembe; 24, 1927. seri-ai Nb. 242,363.

This invention relates to well drilling apparatus and particularly pertains to devices commonly termed core barrels which are em-v ployed to take samples or cores of the formation through which a well is being driven.

In general,.these core barrels include a hollow drill barrel having a drilling shoe at its end which is run intothewell either by a cable or at theend of a rotary drill pipe. Within the drill barrel is an inner core barrel or tube relative to which the drill barrel is movable, so that the drill barrel may be operated to form a core andat the same time force the core tubeover the core or sample to recover it. I I

Prior to my invention, it has been common practice to leave the lower ends of, these core barrels open while the barrel was, being lowered into the hole. This oftenres'ulted in rendering the .core barrel inoperative because foreign material, such as navings from the wall of the hole and other foreign matter,`

lodged in the core barrel, lling the lsame so that when the barrel -was placed in opera-tion at the bottom of the well there Awas no space in lthe core barrel for the core to enter. Also, occasionally foreign matter would pass upwardly through, the core barrel and lodge under the valve at the top of the barrel which lwas provided to permit the exit of fluid trapped in the barrel and hold this valve open,

so that the kcirculating Huid would pass into the core barrel and wash out any core thatmight have been taken.

It is the principal objectof the present invention to overcome this odeficiency in prior structures, by providing a closure for the lower end of co1?J barrels which would effectively obstruct the passage of material other. than fluid into the barrel during the movement of the barrel to the point of operation in the hole, but which may bereleased after the barp rel has reached the point of operation, so as tounobstruct the passage of a core into the barrel. I l

In carrying out the invention into practice, I provide what I prefer to-'teim a screen plug which is fitted-to the lower end of the core barrel, and which will effectively obstruct the passage of material other than fluid into the barrel during the time that the barrel is being lowered into the hole. This screen plu however, is of a diameter that it will pass up into the core barrel when released and I have so connected it to the core. barrel that after the Fig. 2- isa similar view showing the'mp proved device disconnected from the core barrel and moving upwardly therein as the barrel penetrates the formation.

. Fig. 3 is a perspective view of the improved device.

Referring more particularly to the accom- ',panying drawings, 10 indicates a core barrel comprising an outer drill barrel 11 having a drilling shoe 12 at its` lower end. T hisdrilling shoe is described and claimed in my copending application entitled Drilling shoe, filed April 27, 1927, Ser. No. 186,908, while the core barrel structure may lie either of the type shown in my c-o-pending application entitled Rotary corebarrel, filed April 27, 1927,

Ser. No. 186,909, or in my United States Letters Patent#1,611,5,04, entitled Core barrel., issued to me December 21, 1926.

barrel or tube 14 which is adapted` to receive the core when the latter is formed by the drill'barrel. The core barrel 14' advances simultaneously with the drill barrel 11, but

Arranged within the drill barrel 11 is a core the latter'is permitted a. certain amount of of the core-barrel down the hole to the .point of operation. To accomplish this, I- provide f a hollow cylindrical plug 15, the lower end yin diameter and at its upper extremity it is formed with an annular exteriorly projecting shoulder 17. This shoulder is adapted to be engaged by a plurality of flexible fingers 18 secured within the lower end of the core barrel at the inner periphery thereof. These flexible fingers 18 extend upwardly and inwardly and are outwardly yieldable, so that the larger portion of the plug may pass upwardly by the fingers and into the core barrel when released therefrom. It should be stated that these fingers 18 are for the purpose of pinching off a core inserted into the core barrel and to hold it in place while the core barrel is being removedfromtthe well. Such a structure is described and claimed in United States Letters Patent #1,655,644, en-

titled Core retainer for core barrels, issued to me January 10, 1928.

Cooperating with the flexible fingers 18 in supporting the plug at the lower end of the core barrel is a pin 19 which extends diametrically through the plug-with its ends projecting a distance beyond the exterior surface of the plug, so that they will beengaged by the end of the trimmer shoe 16. Thus the plug will be held from `dropping out of 'the core tube by the spring fingers 18, 'while the pin 19 will keep the plug from passing upwardly into the core tube.

-, In its lower end, the plug is formed with a.

plurality of restricted openings 20' so that Huid may pass upwardly into the core barrel. These openings are, however, not large enough to permit any obstructing substances from entering the core tube, while the latter is being lowered into place in the well.

In operation of the device, the plug is fitted to the end of the'core barrel as illustrated in the drawings, and the latter is lowered into v the hole. After reaching the point of operation, the weight of the core barre-l resting on the e dsof the pin 19 will shear the latter and isconnect the plug from the core barrel. The plug 15 will then be free to p'ass upwardly into the core barrel and will do so asthe7 core is pressed .upwardly into the core barrel. After the core has been taken, the entire 1. In combination with a'core barrel, of a hollow plug adapted to fit within'the lower end thereof to I close the same, said plug being of a diameter whereby it may travel upwardly into the core barrel when released therefrom, said plug having a plurality of restricted openings formed therein 'to permit the passage of Huid therethrough, means on the plug engaging the core retainer in the core barrely to support the plug, means carried by the plug engaging the lower end of the core barrel to prevent the passage of the plug upwardly into the core barrel, said lastnamed means being fragile whereby it may be disrupted when the core barrel has reached the pointy of operation in a well so that the plug may be released from the core barrel and travel upwardly therein to permit the entry of a core.

2. In combination with a core barrelyof a plug fitted to the lower end thereof and effectively closing the samegsaid plug being of a diameter permitting:itf` to pass upwardly within the barrel when' disconnected therefrom, means on thev plug engaging the barrel and 'normally preventingl the plug from travelling upwardly into the barrel, said means being fragile and adapted to be rendered ineffective by `imposing the7 weight of the core barrel thereon after the plug reaches the bottom of the hole.

3. -In combination `with a core barrel, of a plug adapted to t Within the lower end thereof to close the same, said plug `being of a 'diameter whereby yit may travel upwardly into the core barrel when released therefrom, means on the plug projecting transversely therefrom andfengaging the core barrel and normally preventing the plug from passing upwardly into the core barrel, said means being fragile and adapted to be disrupted by imposing the weight ofthe core barrel there-l on when the the well.

n "REUBEN C.

plug has engaged the bottom of structure is removed from the well and they core is removed from the tube. As Ithe core is recovered, the plug will be removed and may be used in subsequent operations.

-From the foregoing it is obvious that I have provided a simple and efficient device,

adding considerably to the successful operation of core barrels, which device is of simple and inexpensive construction.

I claim: 

